An employee Exodus would require a drastic surprise for those paying close attention to the company. For various reasons, I would estimate Google and Microsoft

An employee Exodus would require a drastic surprise for those paying close attention to the company. For various reasons, I would estimate Google and Microsoft have historically had the possibility of recruiting from about half the senior Engineers in my niche.. Facebook and Amazon are a bit lower, maybe as low as a quarter. For companies bought by these companies there is a general readjustment as up to about half the engineers who would have refused a job offer from them leave while trying to take the most value in vesting schedules and line up something elsewhere. The "Exoduses" from incompatible buyouts don't really make headlines because 50% over ~3 years with replacement is hard to see from the outside and most tech mergers are catastrophes if both companies' lines were actually supposed to remain profitable.